Head portion of an electric toothbrush



FIG. 1 is an enlarged, perspective view of a head portion of an electric toothbrush showing our new design; and,

FIG. 2 is a top view thereof.

The dashed lines shown in the figures represent environmental subject matter and form no part of the claimed design. The dotted lines shown in the figures represent the border between claimed subject matter and unclaimed subject matter and form no part of the claimed design. 

The ornamental design for a head portion of an electric toothbrush, as shown and described. 